<!DOCTYPE html>
<!-- 导入event事件 -->
<html lang="en" xmlns:v-on="http://www.w3.org/1999/xhtml">
<head>
</head>
<body>
    <div id="app">
        <!-- select选择的数据与message进行绑定 -->
        <select v-model="message">
            <!-- 添加disabled后不可选 -->
            <option value="" disabled>--请选择--</option> 
            <option >A</option>
            <option>B</option>
            <option>C</option>
        </select>
    <span>已选择：{{message}}</span>
    </div>


<!-- 导入vue.js -->
    <script src="http://cdn.jsdelivr.net/npm/vue@2.5.21/dist/vue.min.js"></script>
    <script>
        var vm=new Vue({
            el:"#app",
            data:{
                message:""
            }
            
        })
    </script>
</body>
</html>